Preparation and Performances of Solvent-Free Polyurethane-Based Synthetic Leather Foam Coating
The existing bi-component solvent-free polyurethane(SFPU)synthetic leather foaming method has significant limitations.To develop a new type of blocked SFPU and explore its novel foaming technology,a blocked SFPU was prepared.Firstly,polyether polyols and diphenylmethane diisocyanate(MDI)were copolymerized,then the copolymer was capped with acetoxime(DMKO).The blocked SFPU was mixed with the thermal expansion microspheres(TEMs),preparing a solvent-free polyurethane-based synthetic leather foam coating.Simultaneously,the mechanical properties,foaming ratio,softness,resilience,peel strength,and microstructures of the coating were investigated.The results show that the optimal molar ratio of ternary alcohol to binary alcohol in the raw material is 1∶1,the appropriate capping time is 30 min at 80℃,the optimal curing temperature is 120-130℃,and the optimal amount of TEMs is1%-2%,the obtained coating has a elongation at break of over 600%,a foaming ratio of 2.0-2.5,fine and uniform foam cells,the softness and resilience increased by more than 20%,and a peel strength of over 60 N/3cm,meeting the application requirements of synthetic leather.
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